Incandescent electric lamp coated with a light polarizing material



' Aug. 12, 1941. a H. LAND 2,252,324

INCAHDESCENT ELECTRIC LAMP COATED WITH A LIGHT :OLARIZING MATERIAL Filed 001:. 4, 1938 I a JtgNTOR y? A O NEYS Patented Aug. 12, 1941 o iTEo "STATES PATENT OFFICE INCANDESCENT ELECTRIC COATED WITH A LIGHT POLARIZING MATERIAL Edwin H. Land, Boston, Mass., assignor to Polaroid Corporation, Dover,

- Delaware Del., a. corporation of 7 Claims.

This invention relates to a new and improved .incandescent electric lamp coated with lightpolarizing material.

An object of the invention is to provide such a lamp wherein the coated portion is non-planar.

Another object of the invention is to provide an envelope for an incandescent light source adapted to polarize in a predetermined manner the beam emitted from the source.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises an article 'of manufacture possessing the features, properties, and the relation of elements which will be exemplified in the article hereinafter described and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Figure 1 represents a side view in section of a device embodying one form of the invention;

Fig. 2 represents a view in front elevation of the device shown in Fig. 1; V

Fig.3 represents a modified form of the device shown in Fig. 1;

Fig. 4 represents a still further modification of the invention; and

Fig. 5 is a detailed view in section showing a still further modification of the device shown in Fig. 1.

Heretofore light-polarizing elements of relatively large surface area have been commercially available in two forms. The material: sold under the trade name Polaroid, which comprises a suspension of oriented polarizing particles in a light-transmitting medium, has been available in sheet form or has been laminated toor between light-transmittingsupporting elements, such as sheets of glass or plastic material. It has not lent itself readily to distortion in more than one direction. The sheets or films can be readily formed into cylindrical bodies, but they are not easily distorted from a. planar to a convex or concave form. Furthermore, considerable dim- .culty has been encountered in employing a polar- The other form of polarizing material available commercially comprises an oriented film or layer of polarizing crystals grown or deposited on a supporting plate. In this form of polarizer the which comprises an exceedingly thin layer or film of oriented polarizing particles in a lighttransmitting medium, the particles being present in a highly concentrated condition and the suspension itself having a thickness of approximately .0004 inch or less. Such a film or foil of light-polarizing material may be readily transferred from a support, such for example as a resilient, flexible rubber support, to a surface of any shape or size. It is available in large areas. It may be applied to convex or concave surfaces, or to spherical surfaces, or to plane surfaces so as to form thereon a light-polarizing film adapted to predeterminedly polarize light transmitted by the surface.

-Such a polarizing film may comprise preferablya suspension of needle-shaped polarizing crystals of herapathite or a similar compound in a lighttransmitting suspending medium, such as a cellulosic medium, for example cellulose acetate, or a polymerized vinyl compound such as the compound sold commercially under the trade name Vinylite XYSG. may be formed by rubbing or smearing a suspension of the unoriented crystals upon a suitable support, orientation being eifected by the smearing or rubbing of the suspension.

Transfer of the polarizing film from the initial support to the surface to be coated may be accomplished by applying to the exposed surface of the film or to the surface to be coated an adhesive for the film or a mixture of a solvent and softening agent for the film. The film may .is adapted to conform to the surface to which it is transferred, or to the surface on which it is initially formed. Arcuate, spherical, convex, concave and other curved surfaces may thus be coated with a polarizing film so that the surfaces may be adapted to providing polarizing areas.

While such a method of forming polarizing areas within the scope of this invention is preferred, it is to be understood that other means may be employed without departing from the invention. For example, where the heavier type of polarizing film is employed, or where acoating of the above described type is affixed to a pliable sheet of plastic, the polarizing surface may be curved within the limits of curvature of the film or support. All of such curved polarizing elements may be adapted for use in the present invention.

A principal use for the product of the present The polarizing suspension l a metallic film24 which acts as a reflector. The

filament 26 of the bulb may be positioned at the focus of the parabolic portion of the bulb. The

lens portion 22 of the bulb maybe adapted to' control the spread of the beam emitted from the lamp. The lenticules 28 may be either on the inner face, as shown in the drawing, or the outer face of this portion of the bulb. In the use of the present invention in connection with a device of this kind, the polarizing film may be applied either to the inner face of the metallic reflecting portion '24 or to that face of the lens portion which is left smooth and which may be either the inner or outer face. In the form shown in Fig. l the polarizing film 30 has been applied to the outer face of the lens portion 22 of the bulb,

and in the form shown in Fig. 5, the-polarizing film 50 has been applied to the reflecting portion 24 of the bulb.

In Fig. 3 there is shown a light bulb of the so-called lumiline type, i. e., a long, cylindrical bulb. In the practice of the present invention the outer surface of the envelope 40 of this bulb may be coated in the manner described with a polarizing film or coating. The arrow 42 is to be understood as indicating the direction of orientation of the polarizing axis of the crystals in the coating. The coating may be applied to the envelope of the lamp to give any desired vibration direction to the emitted beam.

In Fig. 4 there isshown an electric light bulb 43 of the usual shape. This also may be coated with a light-polarizing film. -Here the arrows 44 are to be deemed indicative of the direction of the polarizing axis of the film on the surface of the envelope of the bulb. It is to be understood that the film may be applied to the bulb in such a way as to cause light emitted from various portions of the bulb to be polarized in any predetermined manner. Portions of the bulb, for example, may be so coated with the polarizing film that thelight emitted therefrom is vibrating in a direction at right angles to the direction of vibration of light emitted from other portions of the lamp. So also the polarizing film may. be applied only topredetermined portions of the bulb, so that only light rays emitted in a predetermined direction are polarized. All such modifications are to be deemed to fall within the scope of my invention.

Since certain changes may be made in the above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above'description or shown in theaccompanying drawing shall be. interpreted as illustrative and not in a limiting sense.

l The coated surface may be of any desired size and shape. It may be reflecting or light-transmitting, transparent or translucent.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein d escribed, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure as Letters Patent is: I

1. An incandescent lamp comprising, in combination, a filament light source, an envelope therefor a portion at least of which is transparent, at least a portion of said envelope being non-planar, said envelope substantially encompassing said source, a non-planar portion at least of said envelope being coated with a material which polarizes transmitted light, said coating being affixed to and positioned on said envelope to intercept light beams emanating from said source.

2. An incandescent lamp comprising, in combination, a filament light source, an envelope therefor a portion at least of which is transparent, said envelope substantially encompassing said source,.the transparent portion of said envelope being non-planar and being coated with material which polarizes light by transmission thereof, said material being aflixed to said envelope and intercepting beams emanating from said source and traversing the said transparent portion of said envelope.

3. An incandescent lamp comprising, in combination, a filament light source, an envelope therefor a portion at least of which is transparent, said envelope substantially encompassing and being positioned to intercept rays emanating from said source and refiected from the reflecting portion of said envelope.

5. An incandescent lamp comprising a filament light source, an envelope comprising transparent and non-planar reflecting portions and substantially encompassing said source, and a coating of light-polarizing material afiixed to the reflecting surface ofsaid envelope and polarizing light by transmission and positioned to intercept rays emanating from said source and impinging upon said reflecting surface.

6. An incandescent electric lamp having the outer non-planar surface of the transparent envelope thereof adhesively coated with a lightpolarizingmaterial which polarizes by transmission light emanating from said lamp.

7. An electric light bulb having the outer nonplanar surface of the transparent envelope thereof adhesively coated with a suspension of light-polarizing particles in a transparent suspending medium, the particles being so oriented within the medium as to polarize in a. predetermined manner light emanating from within said bulb. 

